Few technologies have more disruptive potential than Docker. Although the company and its namesake technology are barely two years old, almost every major cloud vendor has, or is in the process of, providing support or integration with Docker.

If you aren’t familiar with Docker, Brandon Butler at Network World has come up with one of the best definitions so far:

“Docker is both an open source project and the name of a startup that focuses on Linux Containers. Containers are the idea of running multiple applications on a single host. It’s similar to compute virtualization, but instead of virtualizing a server to create multiple operating systems, containers offer a more lightweight alternative by essentially virtualizing the operating system, allowing multiple workloads to run on a single host.”

Docker’s technology has generated huge excitement and clearly has massive potential, but does that mean everyone should swap out their virtual machines and replace them with containers?

Docker’s advantage

Docker’s containers can be hugely advantageous for anyone involved in cloud-based app development. Containers themselves might not be such an original idea, but Docker’s architecture holds great promise. Its lighter weight makes it a much better fit for widely distributed cloud-based platforms where there’s a need to move workloads to and from different resources.

As depicted in the following diagram, Docker does not need an operating system residing with the app in a virtual machine, nor does it require a hypervisor. Docker’s architecture is a lot simpler than traditional virtualization. It removes the need to collocate applications with an operating system inside a separate virtual machine, which is why it’s easier to move apps from cloud platform to cloud platform. In contrast, virtualization is heavier and that makes it more difficult to deploy, and more of a hassle to move apps between cloud platforms. Apps can therefore be built inside Docker containers, which can easily be moved around from on-premise to cloud, cloud to cloud, wherever you need them to be.

Image credit: Docker

Disrupting DevOps

Docker also has certain advantages for developers. As Charles Babcock writes in Information Week, DevOps necessitates a high level of cooperation with operations managers and developers. Using Docker, developers can create their code without caring where it will be run, and they can make changes to their code without needing to worry about maintenance. Operations managers can accept code that’s already been tested, formatted and is guaranteed to be isolated from other bits of code in the production environment.

“With Docker, developers and operations, two groups that have perennially been at war can sit down at a table where a truce could break out and make it easier for both sides to get their jobs done,” explains Babcock.

The threat to VMware

One of the biggest question marks is whether or not VMware should be worried about the emergence of Docker. Docker’s light weight, simplicity, portability and appeal to developers means VMware cannot afford to just turn a blind eye.

“[Containers] can’t be matched in every way by sophisticated virtualization tools and management,” writes Babcock. “There’s evidence from IBM that containers deploy more quickly and run more efficiently than virtual machines. They can also be more densely packed on servers. That’s a big plus in the cloud, where overall efficiency remains a litmus test of who will thrive and who will die.”

That being said, virtualization does have a number of management advantages in enterprise data centers thanks to its wealth of legacy apps – an advantage it should retain for the foreseeable future. But unfortunately for VMware, that advantage is not likely to last.

“The next generation of applications, many of which will run in the cloud, are more likely to be built with containers in mind rather than virtualization,” writes Babcock. “When applications are composed as assemblies of many moving and distributed parts, containers will be a better fit.”

Virtualized containers, anyone?

For its part, VMware has so far downplayed any fears that Docker might chomp away at its business.

Asked about the competitive threat Linux container technology could pose to the vendor’s virtualization business, VMware CEO Pat Gelsinger said virtual machines are a “proven” technology for handling security, networking and management, and can run both legacy apps and new apps. In contrast, containers don’t offer the security benefits of isolation that are a core part of virtualization.”

But VMware is hedging its bets by incorporating container technology into its own product mix. VMware CTO Kit Colbert recently hinted as much, saying that he believes containerization will live side-by-side with virtualization in the future.

“We (VMware) see containers and virtual machines as technologies that function better together,” wrote Colbert in a blog post this month. “By combining containers and virtual machines, customers can improve their ability to deliver applications without compromising their enterprise IT standards.”

The gist of Colbert’s argument is that container technology is still a bit risky and lacks the kind of management and robustness that VMware’s virtualization systems provide. That means containers might work better when run inside a virtual machine, giving system admins the best of both worlds, he said.

VMware has scheduled several VMworld sessions around the topic, with the theme “better together.” Whether people buy into the message remains to be seen, but it’s clear that the long-held promise of virtualization to enable more efficient optimization of server resources is being effectively addressed by Docker.

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